The present invention relates to a fuel injection device for an internal combustion engine and, more particularly, to a fuel injection device wherein a fuel injection rate can be adjusted in accordance with operating states of the engine.
In general, the performance of an internal combustion engine greatly depends on the method of fuel injection into a combustion chamber. In particular, in a direct fuel injection type of diesel engine, a rate of fuel injection into the combustion chamber directly influences the combustibility of the fuel, and so, greatly influences engine performance.
For example, a diesel engine has a higher combustion noise than that of a gasoline engine when it is idling. In order to reduce idling noise, it is known to decrease an injection rate without decreasing the injection amount of fuel. Furthermore, it is very effective to operate the engine at an intermediate or high speed under conditions such that the injection rate is kept low before the fuel is ignited in the combustion chamber and the rate is abruptly increased at the time of ignition, thereby obtaining high output power.
As may be apparent from the above description, the fuel injection rate must be adjusted in accordance with a given operating state of the engine such that combustion noise is decreased during idling and such that the output power of the engine is increased.